Russian Meteor

Once again we are reminded that we live in a cosmic shooting gallery. With the unannounced arrival of a meteorite over the city of Chelyabinsk in Russia, and the unrelated near miss by asteroid 2012DA14 we can see how delicate the balance of our existence is hear on this planet, and how easily it could be wiped out. The Meteor of 15 February is now known to be the largest recorded object to have encountered the Earth since the 1908 Tunguska event, and it is the only such event known to have resulted in a large number of casualties. The object could be classified as a bolide, 'a large fireball which explodes or disintegrates' and the event has been referred to as an air burst, seeing as how it exploded during its passage through the atmosphere with spectacular and damaging results.

There are a number of estimates on the size and mass of the meteor, but it seems in general it was around 15 metres in size and had a mass, on entering the atmosphere, of some 7000 metric tons. It was travelling at approximately 18 km/second. If you do the maths this gives it a Kinetic energy of 1.134 x 10exp15 Joules. That's equivalent to the explosive power of approximately 300 Kilotons of TNT. In times like this we always seem to compare that with nuclear weapons and so this is around twenty times more than the nuclear weapons dropped by the USA on Japan during WWII. It was fortunate then (or maybe not for those injured) that the meteor exploded some 30 to 50 km above the Earth's surface. Another saving grace was the fact that it's trajectory was at a fairly shallow angle, meaning it travelled through a lot of atmosphere but exploded relatively high. Computer simulations of airburts show that the most dangerous are those that come in heading straight down. This is due to the fact that the most damaging shock waves from such explosions travel straight foreword in front of the trajectory.

For a more global comparison, the Chicxulub impact, which caused the last mass extinction here on Earth some 65 million years ago, was estimated to be equal to 100 million megatons of TNT. However lets not get complacent. This meteor was small, it exploded high in the atmosphere over an area of relatively low population density. It came in at a fortuitous angle and, spectacular as it was, caused only a moderate amount of damage. Many people were unfortunately injured, mostly by flying glass but it could have been a lot worse. The worrying points are we didn't see it coming, we are unprepared for such events and they will happen again. That is inevitable, it's just a matter of time and luck.

A Weighty Matter

How much does a kilogram actually weigh. It's an interesting question, originally it was defined as 'a volume of water equal to the cube of the hundredth part of the metre, at the temperature of melting ice', which is fine, but not very practical. In order to make it easier a standard reference kilogram was created known as the 'The International Prototype Kilogram', known as the IKP, a 39 mm high platinum-iridium alloy cylinder which is stored in a vault at the International Bureau of Weights and Measures in Sèvres, France. This kilo doesn't just weigh a kilogram, it is the kilogram, its the standard against which all other kilograms are weighed. The problem is, it's getting heavier.

It is estimated that pollutants building up on the standard kilogram may have added tens of micrograms to the weight of the IPK over the years. So, how do they know its getting heavier you may ask, what are they measuring it against? Well there are in fact 40 official IPK replicas around the world, and they all appear to be gaining weight at slightly different rates. This presents a problem as this divergence, even at such small levels, causes them all to be out of sync with each other. Now researchers at the University of Newcastle have tried to remove these pesky pollutants by exposing similar surfaces to UV radiation, it is hoped that this will remove the pollutant contamination and should, at least in theory, return the metal to its original weight and hopefully stop this problem.

Why should we care? Well the thing is so many other units of measurement depend on the kilogram. As of 2013 the kilogram was the only SI unit still defined by an artifact. If the kilogram changes, so must the newton, if the newton changes, so must the joule and so on. That's why there are plans to define the kilogram not by a prototype, but in terms of fundamental physical constants, in particular the plank constant. If this goes ahead then hopefully the problem may be fixed once and for all but for now we need a way to keep the standard kilogram just that. One kilogram.

Quantum Smell

There's an old joke that goes “My Dog's got no nose” “No nose? How does he smell?” “Terrible!” It's not very funny but it asks an interesting question, just how do we smell something? Well a controversial new theory suggests that the way we smell involves quantum physics. Following experiments with animals and human it challenges the long held notion that our sense of smell depends only on the shapes of molecules we sniff in the air Instead it suggests that it is the molecules' vibrations that are responsible for their perceived smell.

The traditional idea is that it is the molecules' shapes that is the link to how they it smells One way to test this is to use two molecules of the same shape, but with different vibrations. A recent study suggests that humans can in fact distinguish between the two. Another clue comes from the fact that molecules which include sulphur and hydrogen atoms bonded together all have a wide range of shapes, but they all smell the same, like rotten eggs. Now comes the new theory, this suggest that what actually determines the smell of a molecule is it's vibrations. The sulphur-hydrogen mystery then becomes absolutely clear. This theory explains the mechanism behind how we smell in this way. Molecules can simply be viewed as a collection of atoms on springs, those atoms can move relative to one another. Energy of just the right frequency, a quantum of energy, can cause the springs to vibrate. Now, all this has been suggested before, that it was these vibrations that explained smell. That mechanism is called "inelastic electron tunnelling" and the explanation is that in the presence of a specific molecule, be it the sulphur-hydrogen example from above, an electron within a smell receptor in your nose can jump, or quantum-tunnel, across and deposit a quantum of energy into one of the molecule's bonds, thus setting the spring vibrating. This is what allows us to smell the molecule.

This theory has received scepticism but one way to test the idea is to use two molecules of identical shape but with different vibrations. This can easily be done by replacing a molecule's hydrogen atoms with heavier deuterium. A previous study suggested that human participants could not distinguish between the two, and therefore the vibrations played no role in what we smell. But now a new study published a paper showing that fruit flies can distinguish between the heavier and lighter versions of the same molecule. So a repeat of the human study was done, using even heavier molecules, and it found that humans can indeed distinguish between the two molecules. This study has re-opened the controversy with more traditional biologists still not convinced, but many others are. It seems yet again that we may well live in a universe controlled by the laws of quantum mechanics.

Middle Age Bang

Something strange happen to our planet around the year 775. Last year researchers found evidence that the Earth had been struck by a blast of radiation during the Middle Ages, but there has been debate ever since over what kind of cosmic event could have caused this. Now a study suggests it may have been the result of two black holes or neutron stars merging within our galaxy, producing what is known as a 'Gamma-ray Burst', the most violent event known to happen in the universe.

The research started when ancient cedar trees in Japan were discovered to have an unusually high level of a radioactive type of carbon known as carbon-14. In Antarctica, too, there was a spike in levels of a form of beryllium, beryllium-10, found in ice cores from deep under the surface. These can both be dated very accurately. These rare isotopes are created when intense radiation hits the atoms in the upper atmosphere, suggesting that a blast of energy had once hit the Earth from space. First thoughts were a supernova, an exploding star, may have been the culprit but then ruled out because the debris from such an event would still be visible in telescopes today, we see no such event. Then another group published a paper suggesting that an unusually large solar flare from the Sun could have been the cause. However others disagree because they do not think that the energy produced would tally with the high levels of the isotopes found. Now a group of German researchers have suggested another explanation. A massive explosion that took place within the Milky Way caused when black holes, neutron stars or white dwarfs collide. This type of mergers take just seconds, but produces a vast wave of radiation. They conclude that the event took place some 3,000 to 12,000 light-years away. That is within our own galaxy.

Dramatic as it sounds, the population of Earth at the time would not have noticed anything, such an event would not produce any visible light. However, if such an event were to happen today the result could be disastrous to modern society. If it did happen, at the same distance, it would most likely knock out satellites and affect power grids across the planet. If however such an event were to happen much closer to the Earth, say a few hundred lights years away, it could be enough to destroy the ozone layer, with devastating effects for life on the planet. Fortunately, the likelihood of such a close event is incredibly small, although not zero. Once again we are reminded of how we live in a cosmic shooting gallery.

Living Snow

What do bacteria and snow, specifically snowflakes, have in common? Well it seems bacteria, the first form of live to appear on Earth may have an important role in the formation of snowflakes. Lets start first with bacteria. These little organisms make up much of the total mass of live on this planet. The average human body contains around one and a half kilos of them, approximately the weight of you brain. There are approximately ten times as many bacterial cells in the human body as there are cells, with large numbers of bacteria on the skin and in the gut. The vast majority of the bacteria in the body are rendered harmless by the immune system, and a few are beneficial. However, a few species of bacteria are pathogenic and cause infectious diseases, including such nasty ones as cholera, syphilis, anthrax, leprosy, and bubonic plague. Bacteria have been found living high in the atmosphere, floating around up to 22 miles high they seem immune to the UV radiation at that altitude. Indeed they seem to thrive and even reproduce up there. This is where the connection to snowflakes comes in.

Snow crystals form in the atmosphere when tiny supercooled cloud droplets freeze. These droplets are able to remain liquid at temperatures lower than −18 °C, because to freeze, a few molecules in the droplet need to get together by chance to form an arrangement similar to that in an ice lattice. Then the droplet freezes around this "nucleus". Experiments have shown that this nucleation of cloud droplets only occurs at temperatures lower than −35 °C. In warmer clouds an aerosol particle or "ice nucleus" must be present,or in contact with the droplet to act as a nucleus. Ice nuclei are very rare compared to that cloud condensation nuclei on which liquid droplets form. Dust and biological particles may be effective in this process. This is where bacteria come in to play. In 2008 researchers at Louisiana State University showed that micro-organisms were the most effective ice nucleators present in snow. It seems snowflakes are literally alive.

It seems then that bacteria play an even greater role than previously thought. The idea that snowflakes falling on a snowy day contain living bacteria is a strange, but in my opinion, a beautiful idea. One side effect though of this is for bacteria living high in the atmosphere is this process provides an effective way of moving themselves around and therefore spreading their growth. I will never look at snow in the same way again.

Coin Flip

When you flip a coin, why is it there is a 50/50 chance of it being either Heads or Tails? Sounds like a dumb question but it seems flipping coins has started a whole new debate about how to calculate which one of an infinite number of universes do we live in. The debate comes after a paper posted online a couple of weeks ago by cosmologists Andreas Albrecht and Daniel Phillips. They argue that conventional probability theory, the tool we all use to quantify uncertainty in the real world, has no actual basis in reality. Instead, all probability problems are ultimately about quantum mechanics. "Every single time we use probability successfully, that use actually comes from quantum mechanics," says Albrecht.

So lets wind back a bit. This all traces back to the uncertainty principle, which says we cannot know both a quantum particle's exact position and its momentum. Albrecht and Phillips think that particle collisions within gases and liquids amplify this uncertainty to the scale of everyday objects. They say that it is this which drives all events, including the outcome of a coin flip. Conventional probability, which says the outcome simply arises from two equally likely possibilities, the 50/50 in the case of a coin flip, is nothing more than a useful proxy for measuring the underlying quantum uncertainties. In the case of a coin flip, quantum uncertainty in the position of neurotransmitter molecules in the nervous system of the person flipping the coin may translate into an uncertainty in the number of times a coin turns in the air before being caught. This would ultimately determine whether it lands Heads or Tails. They show a calculation that used estimates for coin size, speed and neurotransmitter uncertainty and were able to show that a quantum sequence of events could give the same probability (50/50) of getting heads or tails just as the conventional calculation does. They say this supports their argument that conventional probability is just a shorthand for some underlying quantum reality.

So why does this all matter if you get the same answer, 50/50? Well it does because there is one use of conventional probability that cannot be traced back to a quantum origin. It is that of predicting the ultimate fate of the universe. The latest theories in cosmology say that our universe is just one part of a vast multiverse containing a large or possibly even an infinite number of other universes. Some of those universes will be exact copies of our own. The mathematics behind the probabilities in quantum mechanics can't cope with that situation though. Cosmologists have until now used conventional probability to determine the chances of us being in one universe or another, but those chances it seems do not have a quantum mechanical origin, they are not the same as a coin flip and therefore we need a new theory of probability in order to explain the multiverse scenario. The next step is to work out what that theory may be. Quantum mechanics just got weirder again.

New Year Discovery

On the first day of a new century, 1 January 1801, the astronomer Giuseppe Piazzi, working at Palermo observatory in Sicily discovered what he first thought was a tail-less comet. After a series of observations, interrupted by illness; and once its orbit was calculated, he realised he had found a 'new planet'. It was named Ceres after the Roman goddess of agriculture and the patron goddess of Sicily. It fitted nicely within Bodes law. between Mars and Jupiter, that strange algebraic “formula” law which seemed to predict the orbital distances of the planets and had just roughly predicted the semi-major axis of Uranus's orbit. Later observations however showed it to be rather small for a Planet and then more and more 'objects' of a similar nature were found reducing Ceres to what was thought to be the largest asteroid. Now though Ceres has had it's nature changed again, and it is now the second largest of what are called 'Dwarf Planets', Pluto being the largest.

Ceres can be tricky to find. It is often just on the verge of human eyesight, even from a dark site, but binoculars and small telescopes show it as a faint star like object. Fortunately at the moment it can be found fairly easily. On December 18th last it reach its maximum brightness of magnitude 6.73 and is handily placed in the constellation of Taurus. Also nearby is Vesta, the second largest asteroid and with Jupiter there also, there are some useful pointers to find Ceres. Any decent astronomy software will assist in finding the strange little dwarf planet. Another way to spot is is to try and take a longish exposure photograph of the area around Taurus and then match it to a star chart.

Ceres is due to be visited by the NASA spacecraft Dawn in 2015, the same year as New Horizons will fly-by Pluto. We should therefore get two good looks at two dwarf planets. Both make interesting targets for a number of reasons but should provide clues as to the origin of the solar system. At the moment, if you get a chance, see if you can find Ceres. It is an interesting spot and many astronomers spend a lifetime without ever giving it notice. The other dwarf planets are a much harder proposition to see.

A Year for Comets?

Predicting the arrival of bright comets can often be like the kiss of death. I am old enough to remember the hype ahead of the arrival of Comet Kohoutek back in 1973. It was predicted to be spectacular, the brightest comet for a hundred years but it came and went as somewhat of a damp squib, particularly for observers in the Northern hemisphere. However, computer modeling has improved and these days predictions are more accurate, but obviously no guarantee. Lets hope that this is the case as in 2013 there are two comets which are predicted to be bright, one spectacularly so, as well as the regular arrival of an old friend.

Firstly Comet ISON, known as Comet 2012 S1, is due to reach it's peak in November and is predicted to be the brightest comet for a long time, possibly even outshining the Full Moon for a brief period. It may possibly even be visible in daylight. This brightness is due to a combination its orbital characteristics and the fact that its orbit is parabolic, meaning therefore this is its first visit to the inner solar system, and therfore 'fresh' in Cometary terms, carrying lots of fresh material to generate a long and spectacular tail. We will see. Second on the list of bright visitors is Comet PANNSTARRS, also known as Comet 2011 L4. This Comet, discovered by the PAN-Starrs telescope in Hawaii back in June 2011, will reach perihelion (it's closest point to the Sun) in March. Predictions are that it may reach a magnitude of 0 (zero) making it easy to spot in the constellation of Pegasus. Finally, we come to Comet Encke. A regular visitor, Comet Encke is a short period Comet with a period of 3.3 years. Next year it reaches perihelion in November when it should be a naked eye object of around magnitude 5 (six being the limit of most peoples eyesight).

So it seems the old adage is true, you wait all day for a bus and then two or three come along at once! Lets hope the predictions pan out then. It's been a few years since we had a decent naked eye Comet, Hale-Bopp being the last good one back in 1997. Apart from that the twentieth century was pretty poor overall for decent Comets. We all hope this year makes up for the recent lack of these beautiful, if unpredictable, visitors.

Super Material

The UK Government has today outlined plans to boost development of the "super-material" Graphene. Graphene, a substance made of pure carbon, with it's atoms arranged in a regular hexagonal pattern similar to graphite, but in a one-atom thick sheet, is one of the lightest, strongest and most conductive materials known, with huge potentials for commercialisation. Now some £21m of funding will go to certain UK universities and their industrial partners in order to “take the technology from the lab to the factory floor”.

Graphene has been called a "Super Material" since it was fist produced in 2005. Gram for gram, it is lighter, stronger and better in every way that nanotechnology experts ever expected. It is many times stronger than steel, and electrons travel through it far faster than through most metals. That and other thermal properties mean that theoretically it has applications in almost every sector of electronics. Other potential areas of use are in aerospace and defence. However, it is tricky to work with. Sheets just one atom thick are difficult to produce, isolate, manipulate and reliably connect to other materials. Those and the other considerable engineering challenges ahead are ones which this latest funding is earmarked to help solve.

The UK Government is hoping that UK Universities and companies will get a lead in the production and development of this new material, with the obvious potential financial benefits. Other nations such as South Korea are already doing just this. Given the UK's general history of loosing it's lead in areas of scientific development, let's hope this money is used wisely.

Wierd Weather

Once again the UK is experiencing extreme weather and over the last few months we have experienced some of the weirdest weather on record. The driest spring for over a century gave way to the wettest recorded Spring in a dramatic turnaround never documented before. Now we are seeing some of the wettest weather on record. Opinion is that there is no evidence that the weather changes were a result of Man-made climate change. But experts from the Environment Agency, the Met Office and the Centre for Ecology & Hydrology warn the UK must plan for periodic swings of drought conditions and flooding.

Overall the weather data shows no huge long term trend, but what we do is more extreme events, and the number of frequency of those extreme events is increasing. There are many views on what is happening, and what is the cause, but the one thing we can agree on is that global weather extremes are becoming more frequent and intense and therefore society must plan ahead in order to manage the impact of these events.

Extreme weather events alone cannot be attributed to climate change but observations of their regularity and distribution suggest something, somewhere, is changing. In order to understand what is going on we need to understand the explain any relationship between climate change and extreme weather. There is no firm evidence yet of this link, but we need to fully understand if there is.